Data security for any organization by using public key infrastructure components and md5, rsa algorithms

IJRET: International Journal of Research in Engineering and Technology ISSN: 2319-1163
__________________________________________________________________________________________
Volume: 02 Issue: 05 | May-2013, Available @ http://www.ijret.org 819
DATA SECURITY FOR ANY ORGANIZATION BY USING PUBLIC KEY
INFRASTRUCTURE COMPONENTS AND MD5, RSA ALGORITHMS
Ruchi Verma1
, Shikha Agrawal2
1
M.Tech. Scholar, 2
Assistant professor, Computer Science & Engineering, CSIT Durg, Chhattisgarh, India,
ruchi.verma393@gmail.com, shikhaagrawal@csitdurg.in
Abstract
In Digital world all type of information are moved around the whole world in the digital form. Securities of these digital data are very
necessary from the intruder, enemies, and unauthorized individuals for any government and non-government organizations. Security
is the protection against danger, criminals and loss. There are many features to security and many applications, ranging from secure
commerce and payments to private communications and protecting passwords. Cryptography is one essential feature for secure
communications. There are two techniques are used in cryptography one is secret key cryptography and another is public key
cryptography. A PKI does not a particular business function; it is providing a foundation for other security services. The primary
function of a PKI is to allow the distribution and use of public keys and certificates with security and integrity. The components of
public key infrastructure are certification authority (CA), certificate revocation, registration authority (RA) and digital certificate.
PKI contain complete information and identifications of there sender and receiver for authentication. In the basis of these identities
PKI provide certificates and authentication for secure communication. In this paper study different components of PKI and there uses
for secure any type of data. This paper presents the performance of a secure application for private organizations that offers services
to both owner and other members of the same organization. The primary focus of this paper is better implementation of PKI with the
help of there algorithms.
Index Terms: Security, Cryptography, Encryption, Decryption, Public key, Private key, Public Key Infrastructure (PKI),
Digital Certificate, Certification Authority (CA), Revocation, Registration Authority (RA).
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1. INTRODUCTION
Every open and private network needs data and network
security for transactions of secret and confidential data among
the government agencies, business and private organizations.
Every sender wants to send there data securely, without any
changes and duplicate of there respective data. In the same
way every receiver wants to receive accurate and exact data
sender to be send. For information security we need privacy or
confidentiality, authentication, message integrity and non-
repudiation. Every user want to authentication for secure
transaction of data means that unauthorized person should not
access, intercept and copy of these data. Sender and receiver
have all the information about together for the identification of
authenticate sender and receiver. Message integrity means
assuring the receiver that the received message should not
been altered it means receiver receives the original data. Non-
repudiation is a mechanism to prove that the sender really sent
this message and sender is authenticate sender. Cryptography
is the science of writing in secret code and hides the message
[1]. Cryptography is not only used for protect data from theft
or alteration or copied, but can also be used for authentication
of sender and receiver. There are three type of cryptographic
algorithm are used for security of data: symmetric/secret key
cryptography, public key cryptography and hash functions [1].
This technique is used in application of advanced societies,
security of ATM cards, electronic commerce and computer
passwords. In cryptography the basic concepts are: cipher,
key, plaintext and cipher text. Cipher is the encryption
algorithm, key is a secret value which is used by cipher, and
plaintext is the original message which is send by sender and
cipher text is the result of encryption of the plaintext [2].
Secret key cryptography is used single private key for both
encryption and decryption. The secret key is known to both
the sender and receiver [3]. At all time sender have risk to
send there secret/private key to the open network. The biggest
problem of this algorithm is the distribution of the private key.
Secret key cryptography is not practical for internet, it is
suitable for encrypt private data and its encryption speed is
very fast [4]. The development of the Internet provides the
way in which the world communicates, but the Internet has
also new problems of Internet communication are trust,
privacy and Security. All sectors of economy need some
formula for trusted and private secure transmission of
electronic data between any two parties. The way of
overcoming these problems are Public Key Infrastructure.
Public key cryptography is based on two key systems. In
public key cryptography without any sharing of secret key
sender and receiver are perform secure communication over
unsecure network [5]. In public key cryptography use one key

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for encryption and other key for decryption. The sender used
receiver’s public key which is known to every one for
encryption. The encrypted data is sent to the receiver, receiver
decrypt this data with his private key. Only receiver can
decrypt the data because no one else has the private key. In
this algorithm the sender only need to know the receiver’s
public key and the receiver’s private key is keep secret. Public
key cryptography is slower but more secure than to the secret
key cryptography. Public key cryptography fulfills all four
aspects or requirement of security. Public Key Infrastructure is
a system of digital signature; digital certificates, Certificate
Authorities, and other registration authorities these
components are used for verify and authenticate the validity of
each entity involved in an online transaction. PKI can be used
for email communication, web browsing, and online banking.
Public Key Infrastructure is the combination of hardware,
software, and people policies with aim to manage, create,
issue, modify, store and remove digital certificates. The main
benefit of the PKI is that it provides a system for distributing
and managing digital certificates, in other words it manages
transmission and storage of Public/Private keys.
2. PUBLIC KEY CRYPTOGRAPHY
Public key cryptography is asymmetric key cryptography in
this technique use two keys. When sender use this algorithm
one key is used for encryption and other key is used for
decryption. PKC is more secure than the secret key
cryptography. PKC have all security requirements for secure
communication. Symmetric key cryptography uses same
key/secret key for both encryption and decryption. The
advantages of symmetric key cryptography are – it is easy to
implement, much faster than PKC and processing power of
symmetric key cryptography is less [6].
Sender Receiver
Fig-1: Symmetric key/same key/private key cryptography.
In symmetric key cryptography single key is used in which
two parties sending there messages to each other must agree to
use the same private key [3]. Now as single key are used
between two parties for secure information transmission, they
need a secure environment for that which is almost
impossible, sharing of private key is risky and unsecure, it is
disadvantage of symmetric key cryptography but in public key
cryptography public key is used for encryption and it does not
need to remain secure. That’s why this type of key is called
public because it does not matter other people know about it.
Sender Receiver
Fig-2: Asymmetric key/ public key cryptography.
PKC provides data integrity, message authentication, and
privacy and non-repudiation aspects for security with digital
signature. Digital signature is component of public key
infrastructure which is used for certification and authentication
of messages. Public Key Infrastructure (PKI) is a set of
hardware, software, product, policies and procedures to create
secure information and secure communication [7]. PKI
provide frame work for components and applications to
combine and achieve the requirement of security.
3. PUBLIC KEY INFRASTRUCTURE
Public Key Infrastructure is group of people, procedure,
hardware, software and policies. All the requirement of
security is fulfillment with the help of PKI components. With
security and integrity, the functions of PKI allow the
distribution and use of public key and certificates [8]. For the
building of other applications, network and data security
components, PKI is playing the role of foundation. In open
network communication when we send any data
electronically, the PKI gives guarantee of the privacy of that
data and guarantee of correct source and destination of that
data. PKI has application for communication and
transactional security is – SSL, IPsec and HTTPS, and for
email security is – S/MIME and PGP [9].
If two parties want to transact business securely and they not
have ever met. In this case they use public key cryptography
for secure transaction services; they must be able to receive
each other’s public keys and identities. They may be
performed this type of secure transaction and if they will
conduct business with more parties then they must rely on a
trusted third party to identity authentication for corresponding
key pair owners and distribution of these public keys [10].
Public key cryptography uses the technique of PKI (Public key
infrastructure). In PKI digital signature technology are used
that makes it important as a basis for security function in
public key distribution.
Encryption Decryption
Plaintext Plaintext
Cipher text
Receiver’s
public key
Receiver’s
private key
Encryption Decryption
Plaintext Plaintext
Cipher text
Secret/Private key

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4. COMPONENTS OF PKI
The basic components of public key infrastructure are
certification authority, registration authority, digital signature,
repositories and archives.
4.1 Digital Signature
In public key cryptography two different keys are used for
encryption and decryption. If sender want to uses his/her
private key for encryption and public key for decryption.
Sender sends encrypted data with there public key to decrypt
this data. In secure transaction of data message integrity are
necessary for authentication of users, digital signature provide
data integrity for the receiver to receive the original public key
from the original sender, it means it proving that a message is
effectively coming from a given sender. In Digital Signature
message is digitally signed with Hash function. Hash function
is used for message digest. These digest message are
encrypted by sender’s private key and than message is
digitally signed and this digitally signed message is attached
with original message, it is called digital signature, is send to
the receiver. From receiver side for successful decryption of
message we need verification of digital signature. Verification
means that no doubt that it is sender’s private key which is
used for encryption of data. From Fig-3 we can easily
understand the process of digital signature.
Fig-3: Digital Signature (Encryption) in sender side.
In the receiver side, receiver separates original message (m)
and encrypted message digest. After separating, receiver apply
Hash algorithm to the message (m) for message digest H (m).
In another side receiver decrypt the digital signature with the
help of sender’s public key and get message digest H (m). If
both sided message digest H (m) are equal, it means that there
is no doubt that it is sender’s private key that encrypted the
message. Fig-4 shows the receiver end process of verifying of
digital signature.
Fig-4: Digital Signature verification in receiver side.
From Fig-3 and Fig-4 we easily understood the digital
signature technology for user authentication and for data
integrity.
4.2 Digital Certificates
A digital certificate is data; the function of digital certificate is
like a physical certificate. It’s included with a person’s public
key that helps others to verify that a key which is used for
encryption is sender’s private key or not. Digital certificates
are used to thwart attempts to substitute one person’s key for
another [11].
A digital certificate has three things:
 A public key of sender.
 One or more digital signatures.
 Identification of users, like name, user ID, etc.
The purpose of digital signature on a certificate is that the
information of certificate is attested by trusted third party
called certification authority. A certificate is basically a public
key with forms of ID attached and cheerful stamp of approval
from trusted third party [11].
4.3 Certification Authority
Certification Authority (CA) is a piece of information that
issues and verifies the certificates. CA proves the identity of
public key’s owner. The trusted third party CA signed and
delivered certificates securely. The CA is operated by the
collection of software, hardware and people.
CA performs four basic PKI functions [10]:
 Creates and signs the certificates.
Message (m) Hash H (m)
Encryption of
hash value
Sender’s private key
Encrypted message
digest
+
Digital Signature is
Send to Receiver
Message (m)
Hash
H (m)
Decryption of
hash value
Sender’s
public
key
Encrypted message
digest
EQUAL?
H (m)
Receiver received digitally
signed message

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 Issues CRLs and maintains certificate status
information.
 Publishes its current certificates and CRLs
 Maintains archives of status information about the
expired certificates that it issued.
A certificate contains:
 The identification of CA.
 The identification of owner.
 The owner’s public key.
 The expiry date of certificate.
 The CA’s signature of that certificate.
Fig-5: CA provide certificate for sender’s public key.
CA provides certificate to the sender’s public key. It means
this public key is certified public key which is used for the
decryption of message in PKC. When receiver receives
certified public key he/she assure for the public key it means
the public key authentic key which is send by authentic
sender.
Fig-6: Certificate is decrypted by CA’s public key
Send signed public key to the receiver which is certified with
CA’s private key. The certified public key is decrypted by
CA’s public key and receiver receives the original sender’s
public key. It prevents modification of the details contained in
the certificate. The CA can be a unit within a organization, a
company or an independent entity [8].
4.4 Registration Authority
Registration authority is intermediate between user and CA.
RA is used for user’s identifications. RA submits the
certificate requests to the CA and verifies certificate contents
for the CA. RA may also reflect information provided by a
third party. The quality of this authentication process
determines the level of trust that can be placed in the
certificates [11]. CA identifies an RA with its name and public
key. RA sends message along with its own signature, CA
verify the RA’s signature and satisfy that the message is
provided by RA. RA’s signature is important for sufficient
protection of its own private key.
5. RSA ALGORITHM
The RSA algorithm is named after Ron Rivest, Adi Shamir
and Leonard Adleman, who invented it in 1977 [8]. RSA is
most widely used public key algorithm. It supports encryption
and digital signature. In RSA algorithm multiply large prime
number together. The multiplication of large prime number is
easy but the factor of product of two prime numbers is
difficult. It is easy to understand and implement. The public
key and private key in RSA are based on very large prime
numbers. The RSA algorithm consists of key generation,
encryption and decryption algorithm.
5.1 Key Generation
1. We choose very large prime integers numbers
randomly p and q.
2. Compute n: n = a * b.
3. Compute x: x = (a-1) * (b-1).
4. Choose an integer e (encryption exponent), Where 1
< e < x, such that: gcd (e, x). gcd- greatest common
divisor.
5. Compute d (decryption exponent), 1 < d < x, such
that: e * d = 1 (mod(x)).
In RSA Key generation there are some important factors –
 The public key is - (n,e).
 The public key is - (n,d).
 The values of p, q and x are private.
 “e” is the public.
 “d” is the private.
5.2 Encryption
Sender represents the plaintext message as a positive integer
m, 1 < m < n and does follows-
1. Obtains the receiver’s public key (n,e).
2. Computes the cipher text C = m^e mod n.
3. Sends the cipher text C to the recipient.
Senders
Public
Key
KA
+
CA
Public
Key
KCA
+
KA
+ Digitally
signed
(Decryption)
K
A
+
Sender’s
identifying
information
CA
Private
Key
K
CA
-
K
A
+
Certificate for
Sender’s
public key,
signed by CA
Digitally
signed
(Encryption)
Sender’s
public key

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5.3 Decryption
Receiver follows:
Receiver uses his own private key to decrypt the message
from cipher text.
m = c^d mod n
6. HASH FUNCTION
The message authentication is one important requirement for
security of any data. It is used to verify the integrity of
message. It is a procedure to verify that received message is
come from the authenticate sender and messages have not
been altered [8]. Hash function is most common cryptographic
technique for message authentication.
Hash function is a cryptographic function that maps a message
of any length into a fixed size bit string called cryptographic
hash value [8]. When we create a digital signature we use hash
function that is digest any message into fixed & manageable
size. Hash function is mathematical function that takes input
data and produced fixed size output which is called message
digest. Hash function H accepts messages of any length and
one-bit digest fixed length outputs are produced. If the input is
even number of character the digest message returns H=0 and
if the message input has odd number of character the digest
message returns H=1 [13].
There are two cryptographic hash functions are used- MD5
(Message Digest 5) and SHA1 (Secure Hash Algorithm 1).
MD5 has an arbitrary input length and produces a 128-bit
digest and SHA1 has input messages of any length less than
2^ 64 bits and produces a 160-bit digest. SHA1 stronger than
MD5 but speed of MD5 is faster than SHA1.
7. METHODOLOGICAL STEPS
The proposed methodology is concern with my previous
papers presentation [14]. In this project first we create
infrastructure for the collection of various set of public keys.
In java secure socket extension used truststore and keystore
file to provide secured transaction between the client and
server.
The Keytool command is used to stores the keys and
certificates in a keystore file. Keystore file protects private
keys with a passward.
7.1 Create Keystore File
The keytool command is used to create the keystore file which
contains public or private key. It allows users to manage their
key pairs and certificates. For creating java keystore file there
are three steps are follows [15]:
1. Create the java key store file (.jks) that only contains
the private key.
2. Generate Certificate signing request (.csr) and have a
certificate generated from it.
3. Import certificate to the keystore.
Keytool is enables users to manage their own key pairs
(public/private) and for self-authentication it uses certificates.
Authentication and data integrity services using digital
signatures, it certifies the user to cache the public keys of there
respective peers. Keytools commands are already discussed in
my previous publication on international conference in IRnet
“Analysis of Public key Cryptographic Systems RSA and
MD5 for Information Security” [16].
7.2 Working Steps
1. Symmetric Encryption: Encrypt the data by using a
symmetric key. After create keystore file the first step
of algorithm is symmetric encrypt.
Symmetric – encrypt:
a) Generate a DES key.
b) Create the cipher.
c) Initialize the cipher for Encryption.
d) Initialize the cipher for decryption.
2. Encrypt the symmetric key using the receiver’s
public key.
3. Store a public key in the set of public key.
4. Create a Message Digest of the data to be
transmitted.
5. Sign the message to be transmitted using digital
signature.
6. Send the data over to an unsecured channel.
7. Validate the Signature using certificate authority.
8. Decrypt the message using Receivers public key from
the set of key to get the Symmetric Key. (Call
Import-key & Test Key pair)
Import – key:
a) Receive a certificate.
b) Validate the certificate
c) Provide a authorize key to user
Test-key-pair:
a) Receive a key from import key
b) Test the key against
c) If true
d) Return
e) Else
f) False
9. Decrypt the data using the Symmetric Key.
10. Compute Message-Digest of data + Signed message.
11. Validate if the Message Digest of the Decrypted Text
matches the Message Digest of the Original Message.

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8. RESULT
The result of this work is providing secure and authenticates
transaction in between organization and there employees. In
an organization the key distribution is very difficult for
unsecure medium, to overcome this problem use asymmetric
key cryptography and public key infrastructure. In this work
uses PKI for provide confidentiality, message integrity,
authentication and non-repudiation. RSA is one of the
algorithms of asymmetric key cryptography. In this work we
use RSA for loading the key, X.509 certificate, DSA for
generating key pairs, MD5 for message digest and AES for
generating symmetric key. These all algorithms are make
transaction more secure, less cost and faster than other
cryptographic system. In this system employees decrypt
encrypted data in less time. PKI have many advantages over
secret key cryptography, for these reason we use this
infrastructure for our system
CONCLUSIONS
Public key infrastructure is highly scalable. PKI users
maintain their own certificates and keys. It provide delegated
trust, a user who has obtained a certificate from a recognized
and trusted certificate authority can authenticate himself to a
server. The very first time he connects to that server, without
having previously been registered with the system. In this
paper we describe working of Public key cryptography, PKI
and their components. In this discussion we discuss about how
to create infrastructure for certificates and digital signatures.
The advantages of public key system are that they provide
authentication and digital signatures. In PKC, key distribution
and private key sharing problem is finished for secure
transactions. So we use PKC in our work.
ACKNOWLEDGEMENTS
I want to thank Mrs. Shikha Agrawal for guiding me and
supporting me in my research work. I want to thank God, my
family and friends, who made all things possible.
REFERENCES:
[1]. SECURITY AND CRYPTOGRAPHY, A tutorial for
cryptography.
[2]. Stallings, W. Cryptography and Network Security:
Principles and Practice, 4th ed. Englewood Cliffs (NJ):
Prentice Hall, 2006.
[3]. Bill Anderson, Certicom Corp, “A Modern Approach to
Information Security”, published in Messaging Magazine,
September/October 1998.
[4]. A seminar report on “Public key infrastructure”.
[5].www.facweb.iitkgp.ernet.in/~sourav/PublicKeyCrypto. pdf
[6]. Ayushi, “A Symmetric Key Cryptographic Algorithm”,
Lecturer, Hindu College of Engineering H.No:438, sec-12,
sonipat, Haryana, 2010 International Journal of Computer
Applications (0975 - 8887) Volume 1 – No. 15.
[7]. A.Jancic and M.J.Warren,” PKI - Advantages and
Obstacles”, School of Information Systems, Faculty of
Business and Law, Deakin University, anaj@deakin.edu.au;
mwarren@deakin.edu.au.
[8]. Dr. Mahesh Motwani, a book on, “Cryptography &
Network Security”, Associate Professor, Department of
Computer Engineering & Deputy Secretary Rajiv Gandhi
Technical university, Bhopal.
[9]. Joel Weise, “Public Key Infrastructure Overview”, SunPS
Global Security Practice, Sun BluePrints™ OnLine - August
2001.
[10]. D. Richard Kuhn, Vincent C. Hu, W. Timothy Polk, Shu-
Jen Chang, “Introduction to Public Key Technology and the
Federal PKI Infrastructure”, National Institute of Standards
and Technology, 26 February 2001.
[11]. Shashi Mehrotra Seth, Rajan Mishra, “Comparative
Analysis of Encryption Algorithms for Data Communication”,
IJCST Vol. 2, Iss ue 2, June 2011, Dept. of CS & IT, MERI
College of Engg. & Tech., ASANDA (near Sampla),
Bahadurgarh, Haryana, India.
[12]. Ray Hunt, “PKI and Digital Certification Infrastructure”,
Proceedings of the 9th IEEE International Conference on
Networks (ICON.01), Associate Professor, Department of
Computer Science, University of Canterbury, New Zealand.
[13]. John Edward Silva, “An Overview of Cryptographic
Hash Functions and Their Uses”, January 15, 2003, GIAC
Security Essentials Practical, Version 1.4b Option 1.
[14]. Ruchi Verma, Vinti Nanda, “A Novel Approach For
Public key Infrastructure”, Int. J. Tech, 2011 ; vol.1; Issue 2,
pg 112-116, Chhatrapati Shivaji Institute of Technology,
Durg, C.G.
[15]. Ruchi Verma, Vinti Nanda, “ANALYSIS OF PUBLIC
KEY CRYPTOGRAPHIC SYSTEMS RSA AND MD5 FOR
INFORMATION SECURITY”, International Conference on
Recent Trends in Control, Communication and Computer
Technology RTCCCT, Raipur, 25th November, 2012.
[16]. Ruchi Verma, Vinti Nanda, “A Novel Approach for
Information Security and public key infrastructure”, National
Conference on Innovative Trends in Management, Science &
Technology ITMAST 2012 , on 8th April 2012 in CCEM,
Raipur, C.G.
BIOGRAPHIES:
Ruchi Verma receives the degree of B.E. in
Computer Science and Engineering from
Raipur Institute of Technology, Raipur C.G.
India in 2010 and she is currently pursuing
M.Tech in Computer Science and
Engineering from Chhatrapati Shivaji
Institute of Technology, Durg C.G. India.
Her research interests include cryptography and information
security.

__________________________________________________________________________________________
Shikha Agrawal is Assistant Professor of
Computer science and Engineering at
Chhatrapati Shivaji Institute of
Technology,Durg, C.G, India. She
receives the degree of B.E. in Computer
Science and Engineering from Chhatrapati Shivaji Institute of
Technology, Durg C.G. India in 2009 and M.E in Computer
Technology and Application from Shri Shankaracharya
College of Engineering and Technology, Bhilai, C.G. India in
2012. Her research interests include image processing and data
mining.

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